The system of the present invention is particularly useful in conjunction with lavage devices for cleaning the hands and arms of persons such as surgeons, nurses, restaurant workers and the like.
Spray type washing mechanisms are well known. Such mechanisms are used in automatic dishwashers and in other types of spray washing machines to clean various products, such as produce and eggs. Most spray type washing machines employ plurality of jets to direct cleaning fluid, supplied under substantially constant pressure, onto the article being cleaned.
A type of cleaning machine which employs intermittent pulses of pressurized cleaning fluid is disclosed in the Patent to Mattingly U.S. Pat. No. 3,393,673. This patent discloses an oral hygiene appliance with a specialized motor pump to supply a pulsating stream of water from a reservoir to a nozzle. The water is discharged at a relatively high pressure in intermittent slugs or pulses at a rate of approximately 1200 pulses per minute.
Another Mattingly U.S. Pat. No. 3,227,158 also is directed to an oral hygiene apparatus employing a reciprocating pump and plunger arranged in a body of liquid to provide a pulsating jet of water or cleaning fluid within a range of 1000 to 1600 cycles per minute. This patent discloses a variation for bypassing a portion of the liquid supplied by the pump to cause a damping effect to produce a smooth waveform (as contrasted with intermittent). This reduces the shock characteristics of the pulsating jet of water. Both of the Mattingly Patents produce the desired effect by means of a specialized multi-part pump, including a relatively large number of parts. A single delivery nozzle (the tooth cleaning jet) is employed.
In hospitals, it is very important for surgeons, nurses, and other operating room personnel to carefully scrub their hands and forearms to remove bacteria which otherwise may contaminate or infect patients. Under emergency conditions, the survival of a patient frequently depends on the time which elapses while the surgical team scrubs before entering the operating room. A typical pre-surgical scrub requires a time duration of 5 (five) to 15 (fifteen) minutes depending upon the type and length of the planned operation.
The manner in which pre-surgical cleansing of the hands and arms of surgeons and operating room personnel has changed very little since the turn of the century. While improved chemicals and drugs have been discovered over the years, the actual technique for accomplishing pre-surgical cleansing has followed the same pattern for years. Scrub brushes and various chemicals are used to free the hands and forearms from bacteria which may contaminate the patient. The scrubbing is done with a brush and dipping of the hands and forearms into different chemical solutions. The scrubbing must be complete and diligent; and, in many cases, is irrating to the skin. This is particularly true for personnel who must scrub frequently during the day (perhaps as many as twenty to thirty times).
Since not all persons scrub in the same manner, the results achieved vary between persons and between scrubs by the same person. In addition, although diligent scrubbing removes surface bacteria, it has been found to have a lesser effect upon bacteria present in the hair follicles and skin depressions. Obviously, any bacteria not removed may act as a contaminant to the patient during surgery or at other times, for example, as a nurse administers to succession of patients.
Another field, in which the potential for the communication of disease to large numbers of persons is present, is in the food handling industry, particularly in restaurants. In the past, it was thought that simple handwashing with a good soap or detergent was sufficient. It has been found, however, even when such hand washing is diligently undertaken by restaurant workers, the bacteria present on the hands are not removed and a high potential is present for the transfer of this bacteria to the food being served to other persons. This was not much of a concern in the past, but the recent discovery of extremely serious and frequently fatal communicable diseases has created an increased awareness of the necessity for following nearly hospital-like cleanliness procedures in the restaurant and food handling businesses.
In an effort to overcome the disadvantages of the manual, brush and disinfectant scrubbing procedures, an automatic lavage machine for washing the hands and forearms of hospital personnel has been developed and is disclosed in the Patent to Bhaskar U.S. Pat. No. 3,757,806. This patent discloses a pulsating hydrojet lavage device which utilizes pulsating jets of pressurized washing fluid for the purpose of quickly preparing personnel for cleanliness of the hands and forearms. The hands and arms of the individual to be scrubbed are inserted into a washing chamber which has a manifold arranged in it to subject the arms and hands to pulsating jets of washing fluid discharged from the manifold. The device of this patent is operated at a pulse frequency of approximately 1500 pulses per minute; and the spray jets of fluid from the manifold cause a compression/decompression effect on the skin, which is particularly effective in removing dirt and bacteria from the hair follicles and skin folds. The device of this patent is operated at a pressure range of approximately 20 PSI to 80 PSI. In a relatively short period of time, approximately twenty (20) to ninety (90) seconds, the resulting cleanliness is equal to or better than a conventional surgical scrub of five (5) minutes or more duration. Although the device of this patent is effective in cleansing the skin, the rapid turning on and off of the cleaning fluid produces considerable shock to the system and results in an extremely loud noise factor. In addition, the high speed pulsating on/off fluid jets, while being an effective cleanser of the skin, also are irrating to the skin, since these high pressure pulses have the effect of "slapping" the skin.
In an effort to overcome some of the disadvantages of the Bhaskar Patent, a lavage machine which produces a cyclically varying pressure has been developed. This machine and its method of operation are disclosed in the Patents to Taldo U.S. Pat. No. 4,402,331 and U.S. Pat. No. 4,465,522. These patents disclose a portable lavage machine which has a recirculating pump in it for withdrawing fluid from a reservoir and supplying it to a cleaning jet manifold. The fluid supplied from the pump first is supplied to a delivery chamber. This chamber has a pair of motor driven impellers in it which rotate past a pair of output orifices to cause cyclical changes in pressure of the fluid delivered from the chamber to the output orifices. The orifices, in turn, are connected to supply fluid to the cleaning jet manifolds in the machine. A motor to rotates the impellers, and the speed of rotation is selected to cause pressure changes from a maximum to a minimum approximately 1200 times per minute.
The shape of the impellers of Taldo is selected to cause the pressure to vary from a minimum (not zero) pressure to some maximum pressure with the transition between the pressure changes being gradual between the two pressure limits. The maximum pressure is maintained for a greater length of time than the minimum pressure, with a gradual, but fairly rapid transition between the pressure changes; so that the resultant pressure waveform is a modified rectangular waveform of an unequal duty cycle. The impeller mechanism significantly reduces the mechanical "banging" of the fluid, as contrasted with the device of Bhaskar. Because of the uneven duty cycles, however, even when two output orifices are provided with the impellers operating 90.degree. out of phase with one another, significant pressure changes are effected at the supply side or input side of the impeller chamber. These pressure changes produce additional stresses on the pump supplying the cleaning fluid to the device as well as creating vibrational stresses on the various parts of the machine.
Other devices have been developed for producing pulsating fluid outputs from a fluid supply. Four such patents are the Patent to Fjermestad U.S. Pat. Nos. 3,111,140; Ishida 3,937,252; Lenglet 4,383,423; and Otto 4,649,955. All four of these patents disclose valve structures to produce pulsed outputs, but none of the valves disclosed in these patents maintain a constant load or constant pressure on the input supply to the devices.
Rotary valves also are well known for directing a fluid path from one or more inputs to a single output or from a single input to selected ones of various outputs. This generally is accomplished by means of an internal rotating part, having a non-linear channel through it, for interconnecting a line located axially with the rotating part to various lines located in different radial positions in a housing. Patents disclosing this type of device are the Patents to Sarver U.S. Pat. No. 2,516,425 and Bass U.S. Pat. No. 3,050,082.
It is desirable to provide a fluid delivery system which is particularly useful in conjunction with lavage machines which does not have the disadvantages of the prior art mentioned above and which delivers a cyclically varying pulsating supply of fluid to the delivery manifolds of the lavage machine, while maintaining a substantially constant pressure on the input line which supplies fluid to the machine.